Optimizing Adaptive Disturbance in Planted Forests: Resource Allocation Strategies for Sustainable Regeneration From Seedlings to Saplings

Climate change intensifies regeneration bottlenecks in plantations via increased drought and phenological shifts, particularly in water-limited temperate ecosystems. As a globally significant afforestation model, China's Three-North Shelterbelt Program exemplifies regeneration challenges in monoculture plantations across temperate ecotones, where successful regeneration depends on precise management timing. Within this context, we investigated Larix principis-rupprechtii regeneration under three thinning intensities (~25%, ~45%, ~65%) across post-thinning recovery stages (short-term: < 3 yr; medium-term: 3-6 yr; long-term: > 6 yr) to develop time-specific regeneration protocols. Moderate thinning (~45%) maximized seedling density (8583 trees hm⁻2) during the medium-term stage. A strategic seedling shifts from shade avoidance (high height-to-diameter ratio, HDR) to shade tolerance (low HDR) occurred at ~3 years post-thinning, enhancing radial growth. Thinning triggered cascading resource effects: increased light availability accelerated litter decomposition (path coefficient = 0.75), subsequently improving soil moisture-nutrient conditions and enzyme activity (0.61). Key regeneration drivers shifted temporally: plant architectural traits dominated short-term regeneration (45.8% variance explained), neighborhood biotic interactions prevailing in the medium term (59.8%), and abiotic factors controlled long-term outcomes (52.6%). These findings provide critical technical guidance for establishing climate-resilient regeneration frameworks in temperate plantations.